moisture reduction by sun-drying for a short period. Lactic fermentation
is then initiated by addition of carbohydrate. This is usually in the form
of rice although traditional saccharifying agents (koji, Japan;look-pang,
Thailand; ang-kak, Philippines) employing mould enzymes may be
added. These accelerate the fermentation, since most LAB are not
amylolytic, and also increases the total acid produced. For example,
Burong-isda containing ang-kak has a lower pH (3.0–3.9) than that
produced with rice alone (4.1–4.5). Garlic is often added along with
the rice as a flavouring ingredient and this may play a similar role in
directing the fermentation as spices do in fermented sausage production.
Garlic is also a source of the fermentable carbohydrate inulin. The
product is normally ready for consumption after about two weeks of
fermentation when the microflora is dominated by yeasts and LAB which
are present at levels around 10^7 cfu g^1 and 10^8 cfu g^1 respectively.
With the exception ofI-sushi, these products are usually cooked before
consumption and this along with the low pH generally guarantees safety.
However, the small, very often domestic-scale, production can lead to
extreme variations in a product’s character and failure to obtain a
satisfactory rapid fermentation inI-sushihas led to outbreaks of botu-
lism in Japan caused byC. botulinumtype E.
9.10 Beer
The popularity of products resulting from the conversion of sugars into
ethanol by yeasts is almost universal and there is hardly a culture without
its own indigenous alcoholic beverage. All that is required is a material
that will furnish sufficient fermentable carbohydrate; a condition fulfilled
by honey, cereals, root crops, palm saps and many fruits, pre-eminently
grapes, but also, apples, pears, plums and others. The ethanol concen-
tration achieved by fermentation is limited by the sugar content of the
raw material and also by the ethanol tolerance of the yeast which is
normally around 14% v/v.Sake, Section 9.12.2 below, is something of an
exception. Potency can be increased by distillation of a fermented wash
to produce spirits such as whisky, vodka, brandy, calvados and arrack,
and ethanol partially purified by distillation can also be added back to a
fermented product to give fortified wines such as port, sherry and
madeira. Here, we will concentrate on a single product which has spread
throughout the world and is now produced more widely than any other
alcoholic drink: European-style beer.
Brewing is thought to have originated in Mesopotamia where it is said
that as much as 40% of total cereal production was used for this
purpose. Because of the relative complexity of the process, it is likely
that beer was a later discovery than wine. The Romans were disinterested
348 Fermented and Microbial Foods